1. Field of the Invention
The present invention relates to a lighting luminaire which more efficiently produces lumens from a compact high intensity fluorescent lamp.
2. Description of the Related Art
The need for lighting large areas has led to the development of a variety of hi-bay and low-bay luminaries. The luminaries, hi-bay and low-bay, found their name in the construction of some types of industrial facilities where a skeletal framework is used to form an interior subspace called a “bay”. Yet, in the lighting industry, this term bay has expanded to encompass almost any large area to be lit. Typical applications of hi-bay and low-bay luminaries include street lighting, parking lot lighting, building flood lighting, sports arena lighting, industrial lighting, gymnasium lighting, warehouse lighting, and retail lighting.
A hi-bay luminaire generally means any installation where the luminaire is mounted high off the ground or floor while the term low-bay generally means any installation where the luminaire is mounted near the area to be illuminated. The Illuminating Engineering Society of North America (IESNA), the authority in lighting, categorizes spaces as either hi-bay (>25 ft.) or low-bay (<25 ft.). However, the terms hi-bay and lo-bay also refer to luminaires designed for these applications, although it is not uncommon to see hi-bay luminaires in low-bay applications, and vice versa. Indoor spaces such as factories, warehouses, retail stores, gymnasiums, and all-purpose rooms are most often lighted by hi-intensity discharge (HID) lamps in a hi-bay or lo-bay luminaire, depending on the distance from the luminaire to the area to be lit. HID lighting luminaires have been highly successful due to their extreme amount of output of light. Sources of HID lighting are typically mercury vapor and high pressure sodium.
The drawbacks to using HID light sources are the use of excessive amounts of energy, poor color rendition, diminishing lumen output over the life of the lamp, no choice of color temperatures, and a lack of high efficiency electronic ballasts to power the HID light sources.
An alternative to standard HID lamp is a metal halide lamp, which provides superior performance and, depending on the ballast, dimming capability. However, many of the drawbacks remain. Recently, manufacturers have begun offering specialized fluorescent luminaires as an alternative for high ceiling applications. These luminaires provide distinct advantages over HID lamps and metal halide lamps. Traditionally, fluorescent lighting has been used in applications where the lamp is within 15 ft. of the area to be illuminated, but new technology has enabled it to be competitive with HID in higher ceiling heights, even over 25 ft. (i.e. In-bay applications). Consequently fluorescent lamps are now being used in many hi-bay and low-bay applications.
Fluorescent lamps have become a substitute for HID and metal halide lamps in many applications. Fluorescent lamps emit diffuse light from long glass tubes. This characteristic of diffusivity has enabled traditional fluorescent lamps to dominate the market for lighting commercial, institutional, and industrial spaces with ceilings less than 15 feet high. The drawback with the traditional fluorescent lamps is the large quantity of luminaries required to light a large area and the lack of efficiency. The large quantities of standard fluorescent luminaires significantly increases the initial installation costs, with no advantage or savings because of the increased labor cost, when compared to the installation of HID luminaires, fluorescent luminaries have not become economically practical in many applications. The traditional fluorescent lamp also lacks the intensity needed for large spacing between lamps at high mounting levels.
More recently, the emergence of more intense and efficient compact fluorescent lamps has enabled fluorescent systems to be used in hi-bay applications. To go along with the latest in high intensity fluorescent lamps, new luminaire design variations addressing aesthetics and some specific user needs have been made. However, fluorescent luminaires have typically utilized long longitudinally extending cylindrical lamps, which are mounted at or slightly below the ceiling level, parallel to the floor surface. These fluorescent lamp luminaires usually have one (1) to four (4) lamps of four foot to eight foot lengths per luminaire, and these luminaires utilize much lower wattage per luminaire than the HID lamp luminaires. The traditional fluorescent luminaires illuminate a rectangular area and they are usually placed in rows mounted end to end.
The recent technology has brought about the high intensity compact fluorescent lamp, which is a four-prong lamp with two sets of joined ends creating a double inverted “U” effect relative to the base. The normal wattage for these double “U” shaped fluorescent lamps is from 5 to 26 wattage per lamp. The biax fluorescent is another new technology utilizing a single elongated narrow “U” effect relative to the base. The normal wattage for these biax lamps is from twenty six (26) to fifty five (55) watts.
The new fluorescent luminaires lamps have several advantages over HID lamps: lower energy consumption, lower lumen depreciation rates, better dimming options, faster start-up and restrike, better color rendition, more pupil lumens, and reduced glare. These advantages make fluorescent luminaires more cost-effective in many applications, and enable them to provide superior lighting to the spaces they illuminate.
However, current luminaries fail to take advantage of the advances made in high intensity fluorescent lamps. Current luminaires have all the lamps in a single optical chamber. This reduces the overall light output or efficiency of the luminaire. When lamps are placed adjacent to one another in a single optical chamber, a portion of the light emanating from one is absorbed by the other(s). Other problems exist with current luminaire designs for compact high intensity fluorescent lamps such as they do not consider maintaining optimum lamp operating temperatures or provide efficient lighting of the area below nor do they provide aesthetically pleasing luminaires for the compact fluorescent lamps.
What is needed is a luminaire for compact high intensity fluorescent lamps that provides efficient lighting to the area below and offers aesthetic appeal.